Apparatus and method for efficient two-way optical communication where transmitter may interfere with receiver

ABSTRACT

An two-way optical communication apparatus, including a transmit element, a receive element, and a transceive processor. The transmit element is coupled to a light pipe, and transmits a first signal. The receive element is coupled to the light pipe, and receives a second signal. The transceive processor directs the transmit element to pause and then resume transmitting the first signal during first intervals, and directs the receive element to sample for the second signal during one or more second intervals within each of the first intervals, where the each of the first intervals is less than a first value and the first intervals occur at a duty cycle no greater than a second value, and where the first and second values are controlled by the transceive processor such that a user perceives the first optical signal as having a constant state for a third interval.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the following U.S. ProvisionalApplications, each of which is herein incorporated by reference for allintents and purposes.

SERIAL FILING NUMBER DATE TITLE 61/872,330 Aug. 30, 2013 APPARATUS ANDMETHOD FOR (RVLV.0107) EFFICIENT TWO-WAY OPTICAL COMMUNICATION WHERETRANSMITTER MAY INTERFERE WITH RECEIVER 61/918,716 Dec. 20, 2013APPARATUS AND METHOD FOR (RVLV.0109) EFFICIENT TWO-WAY OPTICALCOMMUNICATION WHERE TRANSMITTER MAY INTERFERE WITH RECEIVER

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates in general to the field of electronic devices,and more particularly to an apparatus and method that provides forefficient two-way optical communication where an optical transmitter mayinterfere with a corresponding optical receiver.

2. Description of the Related Art

It would be very difficult today to find a consumer electronic devicewhich does not have one or more light emitting diodes (LEDs) disposedtherein to indicate status (e.g., on, off, message waiting, etc.) to auser. LED indicators are used not only in consumer devices, but also indevices in the business and transportation realms.

As a result, a significant amount of attention in the art has beendevoted to decreasing the cost of manufacture of devices with one ormore LED indicators. More specifically, light pipes (also referred to as“light tunnels” or “light tubes”) have been developed to enable thelight from one or more LEDs mounted on a circuit board in a device to betransported efficiently to an area of a display where the light isrequired, thus eliminating a significant amount of hand labor that wouldotherwise be required to fabricate a product. As one skilled in the artwill appreciate, light pipes are generally manufactured from plasticmaterials that transport light via a reflective lining, or transparentsolids that transport the light by total internal reflection. As such,the pipes, according to configuration, are snapped into place on acircuit board, and the board is mounted behind a panel or display.

In addition to being used to display state or status of a given device,light pipes are used to receive light transmitted from outside of thegiven device and to route the light to light sensors internal to thegiven device. Such an application can be as simple as sensing ambientlight in order to control brightness of a display, or it may be morecomplex, such as receiving an optical commissioning data stream fromanother device in order to configure the given device for operation.

For devices that require two-way (i.e., transmit and receive) opticalcommunication, like lower frequency devices, it is important to isolatetransmit circuits from receive circuits in order to preclude thetransmit circuits from interfering with the receive circuits. In manyinstances, isolation amounts to placement of opaque materials such asblack tape in more prevalent interference paths. But the isolation issuebecomes much more prevalent when a single light pipe is shared bytransmit and receive circuits, as is the case in consumer devices wheresize and weight are critical design constraints.

To address isolation in a shared light pipe, one approach requires thattransmit circuits and receive circuits be of such disparate opticalwavelengths that transmissions from the transmit circuits areessentially undetectable by the receive circuits. But this approach isnot very practical in consumer devices that employ inexpensive opticalsensors (e.g., photodiodes) that sense over a broad optical spectrum.

As a result, special purpose light pipes have been developed that routelight to/from a single position on a display, but that allow forseparation of a corresponding light source and light sensor that share asingle light pipe. For example, in U.S. Pat. No. 7,352,930, Lowlesdiscloses a shared light pipe for message indicator and light sensor ona mobile communication device that is of the so-called “Yconfiguration.” A transmit circuit is disposed on one leg of the Y and areceive circuit is disposed on the other leg of the Y, thus allowing forseparation between the transmit circuit and the receive circuit, andalso allowing space to place masking material between the circuits.Interference is still significant within the pipe, and Lowles teachesthat it is prudent to only sense light when the light is not beingtransmitted by the transmit circuit, unless it is desired to confirm thepresence of the transmit circuit. Such a configuration, however, issimplistic in nature, and does not lend itself to applications otherthan using a shared light pipe to sense light when a message waitingindicator is not on.

More particularly, consider a situation where it may be required toemploy a shared light pipe to transmit constant illumination or ablinking indicator, while simultaneously being required to receive anoptical data stream from, say, a commissioning device or a controller.To employ Lowle's technique would require an inordinate amount of timeto receive the optical stream, or it would require that the opticalstream bit rate be on the order of minutes.

Accordingly, what is required is an apparatus and method that providesfor two-way optical communication using a shared light pipe thatsupports optical bit rates much faster than what has been heretoforeprovided, where transmissions must be reliably perceived by a user(i.e., the human eye).

In addition, what is needed is a mechanism that provides a constantillumination or visibly perceptible indication of device state, whichmay also receive an optical data stream via a shared light pipe.

Finally, what is needed is a method for using a shared light pipe totransmit illumination or visibly perceptible device state to a user,while simultaneously receiving optical data from another device.

SUMMARY OF THE INVENTION

The present invention, among other applications, is directed to solvingthe above-noted problems and addresses other problems, disadvantages,and limitations of the prior art. The present invention provides asuperior technique for two-way optical communication via a shared lightpipe. In one embodiment, an apparatus provides for two-way opticalcommunication. The apparatus includes a transmit element, a receiveelement, and a transceive processor. The transmit element is coupled toa light pipe, and is configured to transmit a first optical signalthrough the light pipe. The receive element is also coupled to the lightpipe, and is configured to receive a second optical signal through thelight pipe. The transceive processor is coupled to the transmit andreceive elements, and is configured to direct the transmit element topause and then resume transmitting the first optical signal during firstintervals, and is configured to direct the receive element to sample forthe second optical signal during one or more second intervals withineach of the first intervals, where the each of the first intervals isless than a first value and the first intervals occur at a duty cycle nogreater than a second value, and where the first and second values arecontrolled by the transceive processor such that a user perceives thefirst optical signal as having a constant state for a third interval.

One aspect of the present invention contemplates an apparatus forproviding two-way optical communication. The apparatus has a light pipe,a transmit element, a receive element, and a transceive processor. Thelight pipe is configured to transport illumination from optical signalsbetween ends of the light pipe. The transmit element is coupled to afirst one or the ends, and is configured to transmit a first opticalsignal through the light pipe to a second one of the ends. The receiveelement is coupled to the light pipe, and is configured to receive asecond optical signal transported through the light pipe from the secondone of the ends. The transceive processor is coupled to the transmit andreceive elements, and is configured to direct the transmit element topause and then resume transmitting the first optical signal during firstintervals, and is configured to direct the receive element to sample forthe second optical signal during one or more second intervals withineach of the first intervals, where the each of the first intervals isless than a first value and the first intervals occur at a duty cycle nogreater than a second value, and where the first and second values arecontrolled by the transceive processor such that a user perceives thefirst optical signal as having a constant state for a third interval.

Another aspect of the present invention comprehends a method forproviding two-way optical communication in a shared light pipe. Themethod includes: via a transmit element, transmitting a first opticalsignal through the shared light pipe; pausing and then resuming thetransmitting during first intervals, where each of the first intervalsis less than a first value and the first intervals occur at a duty cycleno greater than a second value, and where the first and second valuesare controlled by a transceive processor such that a user perceives thefirst optical signal as having a constant state for a third interval;and via a receive element, receiving a second optical signal through theshared light pipe during one or more second intervals within each of thefirst intervals.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, features, and advantages of the presentinvention will become better understood with regard to the followingdescription, and accompanying drawings where:

FIG. 1 is a diagram illustrating a frontal view of an electronic deviceaccording to the present invention;

FIG. 2 is a cutaway view of an embodiment the electronic device of FIG.1 taken along axis A-A;

FIG. 3 is a cutaway view of an alternative embodiment the electronicdevice of FIG. 1 taken along axis A-A;

FIG. 4 is a timing diagram showing an optical communication multiplexingtechnique according to the present invention; and

FIG. 5 is a flow diagram illustrating a method according to the presentinvention for full duplex optical communication via a shared light pipe.

DETAILED DESCRIPTION

Exemplary and illustrative embodiments of the invention are describedbelow. In the interest of clarity, not all features of an actualimplementation are described in this specification, for those skilled inthe art will appreciate that in the development of any such actualembodiment, numerous implementation specific decisions are made toachieve specific goals, such as compliance with system-related andbusiness related constraints, which vary from one implementation toanother. Furthermore, it will be appreciated that such a developmenteffort might be complex and time-consuming, but would nevertheless be aroutine undertaking for those of ordinary skill in the art having thebenefit of this disclosure. Various modifications to the preferredembodiment will be apparent to those skilled in the art, and the generalprinciples defined herein may be applied to other embodiments.Therefore, the present invention is not intended to be limited to theparticular embodiments shown and described herein, but is to be accordedthe widest scope consistent with the principles and novel featuresherein disclosed.

The present invention will now be described with reference to theattached figures. Various structures, systems, and devices areschematically depicted in the drawings for purposes of explanation onlyand so as to not obscure the present invention with details that arewell known to those skilled in the art. Nevertheless, the attacheddrawings are included to describe and explain illustrative examples ofthe present invention. The words and phrases used herein should beunderstood and interpreted to have a meaning consistent with theunderstanding of those words and phrases by those skilled in therelevant art. No special definition of a term or phrase (i.e., adefinition that is different from the ordinary and customary meaning asunderstood by those skilled in the art) is intended to be implied byconsistent usage of the term or phrase herein. To the extent that a termor phrase is intended to have a special meaning (i.e., a meaning otherthan that understood by skilled artisans) such a special definition willbe expressly set forth in the specification in a definitional mannerthat directly and unequivocally provides the special definition for theterm or phrase.

Definitions

Integrated Circuit (IC): A set of electronic circuits fabricated on asmall piece of semiconductor material, typically silicon. An IC is alsoreferred to as a chip, a microchip, or a die.

Central Processing Unit (CPU): The electronic circuits (i.e.,“hardware”) that execute the instructions of a computer program (alsoknown as a “computer application” or “application”) by performingoperations on data that include arithmetic operations, logicaloperations, and input/output operations.

Microprocessor: An electronic device that functions as a CPU on a singleintegrated circuit. A microprocessor receives digital data as input,processes the data according to instructions fetched from a memory(either on-die or off-die), and generates results of operationsprescribed by the instructions as output. A general purposemicroprocessor may be employed in a desktop, mobile, or tablet computer,and is employed for uses such as computation, text editing, multimediadisplay, and Internet browsing. A microprocessor may also be disposed inan embedded system to control a wide variety of devices includingappliances, mobile telephones, smart phones, and industrial controldevices.

In view of the above background discussion on light pipes and associatedtechniques employed within present day electronic devices for enablingfull duplex optical communication, a discussion of the present inventionwill now be presented with reference to FIGS. 1-5.

Referring to FIG. 1, a diagram is presented illustrating a frontal viewof an electronic device 100 according to the present invention. Such adevice 100 may be found in virtually every household and businessconfigured as a personal item (e.g., an appliance, an entertainmentdevice, a cell phone, or tablet computer) or as a device disposed in atransportation vehicle (e.g., automobile, train, airplane, ship, etc.)in which it is required to provide for full duplex optical communicationwith a user, another device, or a user and another device, where theelectromagnetic frequency range for optical communication may includethe visible, ultraviolet, and infrared spectrums.

The device 100 may include a housing 102 for enclosing electromechanicalcomponents (not shown) therein. As is alluded to above, a desirableconfiguration for providing optical communication via the device 100 mayinclude use of a light pipe 101 that projects through a correspondinglyshaped interstice in the housing 102. The light pipe 101 may be coveredby a translucent lens or cover (not shown) to provide for filtering,shading, dispersion, etc.

The information transmitted optically via the light pipe (also known asa “light tunnel” or “light tube”) may be merely illumination to providean optically suitable environment for performing other activities. Theinformation transmitted may be indication of the state of the device 100(e.g., on, off, powering up, message waiting, etc.) or may compriseoptically encoded data that is transmitted to a user or to anotherdevice (e.g., configuration information, commissioning information,control commands and responses, etc.).

The device 100 may comprise a plurality of light pipes 101 of variousoptical frequencies in accordance with functions of the device 100,however, for simplicity sake within the present application,illustration of a single light pipe 101 will suffice.

In terms of configuration, the light pipe 101 may be rigid or flexible,as is appreciated by those in the art, and may comprise smooth hollowstructures, generally fabricated from plastic materials, that containlight with a reflective lining, or transparent solids that contain thelight by total internal reflection.

Light pipes, such as the pipe 101 of FIG. 1, are commonly used in anelectronic device 100 to direct illumination from light sources (e.g.,light emitting diodes (LEDs)) mounted on a circuit board to indicatorsand/or backlit controls (e.g., buttons, switches, dials, etc.). Lightpipes 101 facilitate cost-effective fabrication of the device 100 byenabling all light sources to be mounted on a single circuit board,where light from each of the light sources may be directed up and awayfrom the board to where illumination is required. Light pipes 101 may bepurchased in a variety of configurations that may include tens of lightpipes 101 fabricated together in a single module.

Another common use of a light pipe 101 is for reception of opticallytransmitted data. In this application area, rather than directing lightfrom light sources within the device 100 to the outside of the housing102, light is directed from outside of the housing 102 through the lightpipe 101 to optical reception circuits (e.g., photodiodes,phototransistors, etc.) (not shown) disposed within the housing 102. Theoptical reception circuits may be employed to sense ambient opticalconditions around the device 100, or they may be employed to receiveoptically encoded information (e.g., commissioning data, maintenancedata, control data, etc.) that is transmitted by another device.

As one skilled in the art will appreciate, the cost of an electronicdevice 100 that employs light pipes 101 may be markedly less than otherforms of manufacture since costly hand labor is not generally requiredto mount multiple light sources on a single circuit board along with asingle rigid light tube that is employed to transport the multiple lightsources to a display that is removed from the circuit board by severalinches.

Manufacturing ease notwithstanding, one skilled in the art will alsoappreciate that size and weight considerations are also paramount whendeveloping consumer electronics, and thus an essential design constraintfor these electronics requires minimization of parts count, includinglight pipes 101. Accordingly, prior art mechanisms have been developedto allow a single light pipe 101 to both transmit and receive opticalinformation, as is noted to above. However, the present inventors haveobserved that these present day mechanisms are limited in theirapplications. More specifically, these mechanisms do not allow fortwo-way optical communication under conditions in which a light sourcemust be either employed for continuous illumination or employed toindicate a visibly recognizable state (e.g., “ON”, blinking to indicateoperations are occurring, etc.) to a user. Consequently, the constraintsthat illumination/state conditions be visibly recognizable to a user(i.e., the human eye) may preclude use of the light pipe 101 for two-waycommunications because the light source is required to be continuouslyon or it must be on for relatively long periods of time (e.g., 500milliseconds) from a communications perspective. This limitation is thusdisadvantageous for many types of emerging consumer devices.

Another limitation associated with use of a shared light pipe 101 arisesas a result of unintended interference resulting from transmitted lightreflections into a receiving sensor that shares the light pipe 101 witha transmitting element.

The present invention overcomes the above noted limitations, and others,by providing a shared light pipe mechanism that allows for full duplexoptical communication under conditions in which it is required toprovide constant illumination and/or visibly recognizable stateindication. As will be described below with reference to FIGS. 2-5, thepresent inventors have noted that the so-called persistence of visioneffect in humans may be exploited to enable a shared light pipe 101 tobe employed to transmit a constant illumination or visibly recognizablestate indication, as perceived by the human eye, while simultaneouslyallowing for windows of receptive optical sampling during receptionperiods less than a human flicker fusion threshold. Practicallyspeaking, the present inventors have determined that these receptionperiods should be roughly no greater than 40 milliseconds and shouldoccur at an approximately 10 percent duty cycle. That is, during theperiod (“transmission period”) for which it is required to provideconstant illumination or visibly recognizable state indication, one ormore reception periods of roughly no greater than 40 milliseconds may bescheduled at a maximum of an approximately 10 percent duty cycle. Forexample, if the device 100 has a transmission period of 500milliseconds, according to the present invention, five 10-millisecondreception periods may be opened every 100 milliseconds. By exploitingpersistence of vision in this manner in a device 100 according to thepresent invention, optical communication may occur between two devicesor two devices and a user.

In addition to providing for perceived full duplex optical communicationvia a shared light pipe 101, the present invention lends itself well toconsumer electronics devices that include a light pipe 101 comprising anoptical transmitter (i.e., a light source such as, but not limited to,an LED) and optical receiver (i.e., a light sensor such as, but notlimited to, a photodiode, photoresistor, or phototransistor) that arelocated in proximity such that the optical properties of a correspondinglight pipe cause a reflection of the transmitter's data into thereceiver.

Now referring to FIG. 2, a cutaway view 200 is presented of anembodiment the electronic device 100 of FIG. 1 taken along axis A-A. Thedevice 100 may include a housing 202 having a light pipe 201 of the wellknown Y configuration that is disposed through a correspondinginterstice in the housing 202. The light pipe 201 may be configured asis described above having an internal reflective surface 205 that allowsfor transmission of light from an optical transmitter 212 to outside ofthe housing 202 and for reception of light from outside the housing 202into an optical receiver 214. The device 100 may further include anoptical barrier 204 embodied as black tape or paint as shown in FIG. 2to optically isolate transmit and receive paths within the light pipe201 by minimizing unintended reflections from the transmitter 212 intothe receiver 214.

The device 100 may further comprise a transceive processor 211 that iscoupled to the transmitter 212 via bus 213 and to the receiver 214 viabus 215. In one embodiment, the transmitter 212 may be disposed as alight source such as, but not limited to, an LED that receives a voltageor current via bus 213 and responsively emits light in a wavelengthwithin the optical frequency range as noted above. In one embodiment,the receiver 214 may be disposed as a light sensor such as, but notlimited to, a photodiode or phototransistor that receives light via thelight pipe 201 and that converts the light into a corresponding voltageor current, which is provided to the transceive processor 211 via bus215.

In operation, the transmitter 212 is employed generally forcommunication with a human eye (not shown) that exploits the persistenceof vision effect. During periods where a light transmitted through theinterstice is required to be perceived by the eye as being on, thetransceive processor 211 directs the transmitter 212 via bus 213 to turnoff for one or more reception periods that are imperceptible to the eye,as is described above, and during the one or more reception periods thetransceive processor 211 samples the output of the receiver 214 via bus215. Accordingly, incoming optical data may be sampled while stillproviding for a perceived constant illumination or visibly recognizablestate indication. The present inventors note that the perceived constantillumination/state indication may also be employed as part of amodulated transmission from the device 100 to the human eye. Forexample, a 500 millisecond transmission interval time followed by a 500millisecond period when the transmitter 212 is off may be used toindicate a status message to a the human eye. Accordingly, the receiver215 may be sampled by the transceive processor 211 during the 500millisecond period when the transmitter 212 is off, and also during the500 millisecond transmission period, but during the 500 millisecondtransmission period, one or more reception periods as described aboveare controlled by the transceive processor 211 to continue to allow forsampling of incoming optical data.

In one embodiment, the transceive processor 211 may schedule1-millisecond reception periods every 10 milliseconds duringtransmission intervals, though the present inventors note that desiredvalues for the reception interval and duty cycle may be established viaprogramming in closed loop fashion, or they may be fixed based on thecharacteristics of the transmitter 212, the receiver 214, and intendedfunctions of the device 100.

In another embodiment, the device 100 may be employed to transmit andreceive optical data to/from a corresponding optical device (not shown)rather than to the human eye, where the bit rate of the transmitted datais substantially higher than the bit rate of the data transmitted by thecorresponding optical device. Accordingly, while scheduling receptionperiods as described above within the device 100 for sampling of thereceiver 214 during transmission intervals, the corresponding opticaldevice may sample for data that is transmitted by the device 100 withoutunacceptable sampling errors since the bit rate of data transmitted bythe device 100 is substantially higher. In one embodiment, thetransmitted bit rate of the device 100 is at least 10 times that of thecorresponding optical device.

The present inventors note that reception intervals and associated dutycycles may be dynamically changed by the transceive processor 211according to ambient light level of the environment around the device100. During reception periods when the receiver 214 is sampling forincoming optical data, an analog light intensity reading may also betaken by components within the receiver 214. In this way the device 100may sense ambient light level of the surrounding environment and, as aresult of changing ambient light level, the transceive processor 211 mayemploy the analog intensity value to adjust the reception intervals andduty cycles as a function of the surrounding environment, thus enablingthe device 100 to decrease/increase perceived brightness of thetransmitted light and achieve a balanced cosmetic appearance to users inboth direct sunlight and darkened rooms. To the casual observer, suchreal-time adjustments are not immediately noticeable; however, thepresent inventors not that such modifications to reception intervals andduty cycles may be employed to mask undesirable mechanical structureswithin the device 100 along with cast shadows of metallic, fiberglass,and/or plastic internal components within the device 100, which wouldotherwise be particularly noticeable when the device 100 is utilized ina dark room. The present inventors also note that adjusting thereception intervals and duty cycles not only provides cosmetic andaesthetic benefits, but also energy savings, and ambient optical noiseimmunity when required.

The transceive processor 211 according to the present invention isconfigured to perform the functions and operations as discussed above.The transceive processor 211 comprises logic, circuits, devices, ormicrocode (i.e., micro instructions or native instructions), or acombination of logic, circuits, devices, or microcode, or equivalentelements that are employed to execute the functions and operationsaccording to the present invention as noted. The elements employed toaccomplish these operations and functions within the transceiveprocessor 211 may be shared with other circuits, microcode, etc., thatare employed to perform other functions and/or operations within thetransceive processor 211. According to the scope of the presentapplication, microcode is a term employed to refer to a plurality ofmicro instructions. A micro instruction (also referred to as a nativeinstruction) is an instruction at the level that a unit executes. Forexample, micro instructions are directly executed by a reducedinstruction set computer (RISC) microprocessor. For a complexinstruction set computer (CISC) microprocessor, complex instructions aretranslated into associated micro instructions, and the associated microinstructions are directly executed by a unit or units within the CISCmicroprocessor.

The transceive processor 211 may comprise a microprocessor or othercentral processing unit (CPU) that executes one or more applicationprograms disposed in a memory (not shown) to perform the transmissionand reception functions described above. The memory may be eitherinternal or external to the CPU. The transceive processor 211 mayfurther comprise additional electronic circuits (e.g., digital-to-analogconverters, analog-to-digital converters) configured to couple themicroprocessor/CPU to the transmitter 212 and receiver 214 viarespective busses 213, 215.

Turning to FIG. 3, a diagram 300 is presented of a cutaway view of analternative embodiment the electronic device 100 of FIG. 1 taken alongaxis A-A. The device 100 may include a housing 302 having a light pipe301 that is disposed through a corresponding interstice in the housing302. The light pipe 301 may be configured as is described above havingan internal reflective surface 305 that allows fortransmission/reception of light from/to an optical transceiver 321 thatmay be employed to transmit and receive optical signals.

The device 100 may further comprise a transceive processor 311 that iscoupled to the transceiver 321. In one embodiment, the transceiver 321may comprise a combined light source and light sensor, as these elementsare described with reference to FIG. 2, disposed in relative proximityto the light pipe 301. In another embodiment, the transceiver 321 maycomprise a separate light source and light sensor, with no opticalbarrier in between them. In contrast to the embodiment of FIG. 2, thesource and sensor share the same internal reflective surface 305 withinthe light pipe 301 rather than being configured as a Y.

In operation, optical transmit and receive elements within thetransceiver 321 function substantially as like elements are describedabove with reference to FIG. 2, except that the transmit and receiveelements within the transceiver 321 share the same reflective surface305 within the pipe. Consequently, it is impractical to employ maskingmaterial to minimize unintended reflections from transmit element toreceive element. However, because the technique according to the presentinvention employs the persistence of vision effect, two-waycommunication is enabled at the device 100 to a user and from anotherdevice, or between the device 100 and another device, as is describedabove.

During periods where a light transmitted through the interstice isrequired to be perceived by the eye as being on, the transceiveprocessor 311 directs the transmit element within the transceiver 321 toturn off for one or more reception periods that are imperceptible to theeye, as is described above, and during the one or more reception periodsthe transceive processor 321 samples the output of the receive elementwithin the transceiver 321. Accordingly, incoming optical data may besampled while still providing for a perceived constant illumination orvisibly recognizable state indication. In addition, the perceivedconstant illumination/state indication may also be employed as part of amodulated transmission from the device 100 to the human eye. Forexample, a 500 millisecond transmission interval time followed by a 500millisecond period when the transmit element is off may be used toindicate a status message to a the human eye. Accordingly, the receiveelement may be sampled by the transceive processor 321 during the 500millisecond period when the transmit element is off, and also during the500 millisecond transmission period, but during the 500 millisecondtransmission period, one or more reception periods as described aboveare controlled by the transceive processor 311 to continue to allow forsampling of incoming optical data.

In one embodiment, the transceive processor 311 may schedule1-millisecond reception periods every 10 milliseconds duringtransmission intervals, though the present inventors note that desiredvalues for the reception interval and duty cycle may be established viaprogramming in closed loop fashion, or they may be fixed based on thecharacteristics of the transceiver 321, and intended functions of thedevice 100.

In another embodiment, the device 100 may be employed to transmit andreceive optical data to/from a corresponding optical device (not shown)rather than to the human eye, where the bit rate of the transmitted datais substantially higher than the bit rate of the data transmitted by thecorresponding optical device. Accordingly, while scheduling receptionperiods as described above within the device 100 for sampling of thereceiver element during transmission intervals, the correspondingoptical device may sample for data that is transmitted by the device 100without unacceptable sampling errors since the bit rate of datatransmitted by the device 100 is substantially higher. In oneembodiment, the transmitted bit rate of the device 100 is at least 10times that of the corresponding optical device.

The present inventors note that reception intervals and associated dutycycles may be dynamically changed by the transceive processor 311according to ambient light level of the environment around the device100. During reception periods when the transceive processor 311 issampling the receive element for incoming optical data, an analog lightintensity reading may also be taken by components within the transceiver321. In this way the device 100 may sense ambient light level of thesurrounding environment and, as a result of changing ambient lightlevel, the transceive processor 311 may employ the analog intensityvalue to adjust the reception intervals and duty cycles as a function ofthe surrounding environment, thus enabling the device 100 todecrease/increase perceived brightness of the transmitted light andachieve a balanced cosmetic appearance to users in both direct sunlightand darkened rooms.

The transceive processor 311 according to the present invention isconfigured to perform the functions and operations as discussed above.The transceive processor 311 comprises logic, circuits, devices, ormicrocode (i.e., micro instructions or native instructions), or acombination of logic, circuits, devices, or microcode, or equivalentelements that are employed to execute the functions and operationsaccording to the present invention as noted. The elements employed toaccomplish these operations and functions within the transceiveprocessor 311 may be shared with other circuits, microcode, etc., thatare employed to perform other functions and/or operations within thetransceive processor 311. According to the scope of the presentapplication, microcode is a term employed to refer to a plurality ofmicro instructions. A micro instruction (also referred to as a nativeinstruction) is an instruction at the level that a unit executes. Forexample, micro instructions are directly executed by a reducedinstruction set computer (RISC) microprocessor. For a complexinstruction set computer (CISC) microprocessor, complex instructions aretranslated into associated micro instructions, and the associated microinstructions are directly executed by a unit or units within the CISCmicroprocessor.

The transceive processor 311 may comprise a microprocessor or othercentral processing unit (CPU) that executes one or more applicationprograms disposed in a memory (not shown) to perform the transmissionand reception functions described above. The memory may be eitherinternal or external to the CPU. The transceive processor 311 mayfurther comprise additional electronic circuits (e.g., digital-to-analogconverters, analog-to-digital converters) configured to couple themicroprocessor/CPU to the transceiver 321.

Turning now to FIG. 4, a timing diagram 400 is presented showing anoptical communication multiplexing technique according to the presentinvention. The diagram 400 depicts a transmit signal 401, such as may beprovided by the transceive processor 211, 311 of FIGS. 2-3 to direct thetransmitter 212 or transmit element within the transceiver 321 totransmit light into the light pipe 201, 301. The diagram 400 also showsa receive signal 403, such as may be provided by the transceiveprocessor 211, to direct the receiver 214 or receive element within thetransceiver 321 to sample light received into the light pipe 201, 301from another device. The diagram 400 further includes an incomingoptical signal 405, such as may be transmitted by another device intothe light pipe 201, 301. The diagram 400 depicts a scenario where thelight source of the device 100 is to be perceived by the user as beingilluminated, that is, a scenario where the transmission interval isgreater than the time depicted in the diagram 400.

Operationally, to maintain persistence to the human eye, in oneembodiment, the transceive processor 211, 311 controls the states of thetransmit and receive signals 401, 403 according to configuration of thereception intervals and duty cycles within the transceive processor 211,311. Reception periods 402, 404 occur between times T1 and T2, andbetween times T3 and T4, where the transmit signal is in an off stateand the receive signal is in an open state. The present inventors notethat the period that the transmit signal 401 is in an off stateindicates the reception interval and the period between off states ofthe transmit signal 401 indicates the duty cycle. Accordingly, thoughthe receive signal 403 is shown in an open period 404 approximatelyequal to the period when the transmit signal 401 is off, the presentinvention allows for a plurality of open periods 404 within thereception interval 402 to provide for sampling of the incoming signal405.

Referring now to FIG. 5, a flow diagram 500 is presented illustrating amethod according to the present invention for full duplex opticalcommunication via a shared light pipe, such as the light pipe 201, 301of FIGS. 2-3. Flow begins at block 501, where a device 100 according tothe present invention is operating to communicate illumination or statecondition to a user. Flow then proceeds to decision block 502.

At decision block 502, an evaluation is made to determine if atransmitter within the device 100 is required to be perceived by theuser as being on. If not, then flow proceeds to block 503. If so, thenflow proceeds to block 504.

At block 503, one or more receive windows are allowed to be opened tosample for incoming optical data received by the light pipe 201, 301.Flow then proceeds to decision block 502.

At block 504, a receive window, if open, is closed, and the transmitteris set to an on state to provide light through the light pipe 201, 301.Flow then proceeds to block 505.

At block 505, a transmitter on state timer is initiated. In oneembodiment, the on state timer is approximately 90 percent of the dutycycle corresponding to a reception interval for the device 100. Flowthen proceeds to decision block 506.

At decision block 506, an evaluation is made to determine if the onstate timer has timed out. If not, then flow proceeds to decision block506. The transmitter remains in an on state and no receive sampling isallowed.

At block 507, the transmitter is set to an off state, ceasingillumination, and one or more receive windows may be opened according todevice function in order to sample incoming optical signals. Flow thenproceeds to block 508.

At block 508, a transmitter off state timer is initiated. The value ofthe off state timer defines the reception interval for the device 100,and the value of the off state timer divided by the sum of the off stateand on state timers determines the duty cycle for the device. Flow thenproceeds to block 509.

At block 509, incoming light is sampled from the light pipe 201, 301during one or more receive windows that occur during the receptioninterval defined by the off state timer. During the one or more receivewindows, the incoming light may be sampled one or more times. Flow thenproceeds to decision block 510.

At decision block 510, an evaluation is made to determine if the offstate timer has timed out, thus ending the reception interval. If not,then flow proceeds to block 509. If so, then flow proceeds to block 502.

The method continues until such time as the device 100 is placed in aninoperative state or turned off.

Although the present invention and its objects, features, and advantageshave been described in detail, other embodiments are encompassed by theinvention as well. For example, the transceive processor 211, 311 may beconfigured such that high bit rate data may be transmitted during theperiods outside of when receive sampling windows are open (404 in FIG.4) at a rate imperceptible to the human eye such that the light sourceis perceived to be either on or off for these periods, as is appropriatefor indicated function. In this embodiment, the device 100 transmitsoptical data at a bit rate that is substantially faster than the bitrate which it samples during the reception intervals.

Alternatively, a data encoding scheme may be employed to allow fortransmit waveforms from the device 100 where short duration transmitteroff periods are not construed by a receiving device as being off, thatis, interpreted as a logical zero. In this alternative scheme, thedevice 100 may transmit optical data at a bit rate that is substantiallyslower than the receiving device's bit rate which is sampled by thedevice 100.

Portions of the present invention and corresponding detailed descriptionare presented in terms of software, or algorithms and symbolicrepresentations of operations on data bits within a computer memory.These descriptions and representations are the ones by which those ofordinary skill in the art effectively convey the substance of their workto others of ordinary skill in the art. An algorithm, as the term isused here, and as it is used generally, is conceived to be aself-consistent sequence of steps leading to a desired result. The stepsare those requiring physical manipulations of physical quantities.Usually, though not necessarily, these quantities take the form ofoptical, electrical, or magnetic signals capable of being stored,transferred, combined, compared, and otherwise manipulated. It hasproven convenient at times, principally for reasons of common usage, torefer to these signals as bits, values, elements, symbols, characters,terms, numbers, or the like.

It should be borne in mind, however, that all of these and similar termsare to be associated with the appropriate physical quantities and aremerely convenient labels applied to these quantities. Unlessspecifically stated otherwise, or as is apparent from the discussion,terms such as “processing” or “computing” or “calculating” or“determining” or “displaying” or the like, refer to the action andprocesses of a computer system, a microprocessor, a central processingunit, or similar electronic computing device, that manipulates andtransforms data represented as physical, electronic quantities withinthe computer system's registers and memories into other data similarlyrepresented as physical quantities within the computer system memoriesor registers or other such information storage, transmission or displaydevices.

Note also that the software implemented aspects of the invention aretypically encoded on some form of program storage medium or implementedover some type of transmission medium. The program storage medium may beelectronic (e.g., read only memory, flash read only memory, electricallyprogrammable read only memory), random access memory magnetic (e.g., afloppy disk or a hard drive) or optical (e.g., a compact disk read onlymemory, or “CD ROM”), and may be read only or random access. Similarly,the transmission medium may be metal traces, twisted wire pairs, coaxialcable, optical fiber, or some other suitable transmission medium knownto the art. The invention is not limited by these aspects of any givenimplementation.

The particular embodiments disclosed above are illustrative only, andthose skilled in the art will appreciate that they can readily use thedisclosed conception and specific embodiments as a basis for designingor modifying other structures for carrying out the same purposes of thepresent invention, and that various changes, substitutions andalterations can be made herein without departing from the scope of theinvention as set forth by the appended claims.

The invention claimed is:
 1. An apparatus for providing two-way opticalcommunication, the apparatus comprising: a transmit element, coupled toa light pipe, configured to transmit a first optical signal through saidlight pipe; a receive element, also coupled to said light pipe,configured to receive a second optical signal through said light pipe;an optical barrier, coupled to the light pipe, configured to at leastpartially isolate transmit and receive optical paths within splitportions of the light pipe; and a transceive processor, coupled to saidtransmit and receive elements, configured to direct said transmitelement to suspend transmitting said first optical signal during aplurality of reception periods, and configured to direct said receiveelement to sample for said second optical signal during one or moresampling intervals within each of said reception periods, wherein saideach of the plurality of reception periods last for a duration of timeno greater than 40 milliseconds, and the plurality of reception periodsoccur in the first optical signal at a duty cycle no greater than 10percent.
 2. The apparatus as recited in claim 1, wherein said first andsecond optical signals are at wavelengths in a range comprising thevisible, ultraviolet, and infrared spectrums.
 3. The apparatus asrecited in claim 1, wherein said transmit element comprises a lightemitting diode.
 4. The apparatus as recited in claim 1, wherein saidreceive element comprises a phototransistor.
 5. The apparatus as recitedin claim 1, wherein the receive element is configured to sense anambient light level of the surrounding environment during the receptionperiods, and the transceive processor employs an analog intensity valueto adjust the durations of time and the duty cycles of the receptionperiods according to the sensed ambient light level.
 6. The apparatus asrecited in claim 1, wherein said transceive processor directs saidtransmit element to transmit optical data in the first optical signalduring periods outside of the plurality of reception periods, andwherein said optical data is transmitted at a bit rate faster than athreshold optical data bit rate.
 7. The apparatus as recited in claim 1,wherein said transceive processor directs said transmit element totransmit optical data in the first optical signal at a bit rate fasterthan a threshold optical data bit rate, but slower than that of saidsecond optical signal.
 8. An apparatus for providing two-way opticalcommunication, the apparatus comprising: a light pipe, configured totransport illumination from optical signals between ends of said lightpipe; a transmit element, coupled to a first one or said ends,configured to transmit a first optical signal through said light pipe toa second one of said ends; a receive element, coupled to said lightpipe, configured to receive a second optical signal transported throughsaid light pipe from said second one of said ends; an optical barrier,coupled to the light pipe, configured to at least partially isolatetransmit and receive optical paths within split portions of the lightpipe; and a transceive processor, coupled to said transmit and receiveelements, configured to direct said transmit element to suspendtransmitting said first optical signal during a plurality of receptionperiods, and configured to direct said receive element to sample forsaid second optical signal during one or more sampling intervals withineach of said reception periods, wherein said each of the plurality ofreception periods last for a duration of time no greater than 40milliseconds, and the plurality of reception periods occur in the firstoptical signal at a duty cycle no greater than 10 percent.
 9. Theapparatus as recited in claim 8, wherein said first and second opticalsignals are at wavelengths in a range comprising the visible,ultraviolet, and infrared spectrums.
 10. The apparatus as recited inclaim 8, wherein said transmit element comprises a light emitting diode.11. The apparatus as recited in claim 8, wherein said receive elementcomprises a phototransistor.
 12. The apparatus as recited in claim 8,wherein the receive element is configured to sense an ambient lightlevel of the surrounding environment during the reception periods, andthe transceive processor employs an analog intensity value to adjust thedurations of time and the duty cycles of the reception periods accordingto the sensed ambient light level.
 13. The apparatus as recited in claim8, wherein said transceive processor directs said transmit element totransmit optical data in the first optical signal during periods outsideof the plurality of reception periods, and wherein said optical data istransmitted at a bit rate faster than a threshold optical data bit rate.14. The apparatus as recited in claim 7, wherein said transceiveprocessor directs said transmit element to transmit optical data in thefirst optical signal at a bit rate faster than a threshold optical databit rate.
 15. A method for providing two-way optical communication in ashared light pipe, the method comprising: while, via a transmit element,transmitting a first optical signal through the shared light pipe:suspending said transmitting during a plurality of reception periods,wherein said each of the plurality of reception periods last for aduration of time no greater than 40 milliseconds, and the plurality ofreception periods occur in the first optical signal at a duty cycle nogreater than 10 ; and via a receive element, receiving a second opticalsignal through the shared light pipe during one or more samplingintervals within each of said reception periods, wherein an opticalbarrier is coupled to the light pipe, and configured to at leastpartially isolate transmit and receive optical paths within a splitportion of the light pipe.
 16. The method as recited in claim 15,wherein the first and second optical signals are at wavelengths in arange comprising the visible, ultraviolet, and infrared spectrums. 17.The method as recited in claim 15, wherein the transmit elementcomprises a light emitting diode.
 18. The method as recited in claim 15,wherein the receive element comprises a phototransistor.
 19. The methodas recited in claim 15, wherein the receive element is configured tosense an ambient light level of the surrounding environment during thereception periods, and the transceive processor employs an analogintensity value to adjust the durations of time and the duty cycles ofthe reception periods according to the sensed ambient light level. 20.The method as recited in claim 15, further comprising: transmittingoptical data in the first optical signal during periods outside of theplurality of reception periods, and wherein said optical data istransmitted at a bit rate faster than a threshold optical data bit rate.21. The method as recited in claim 15, further comprising: transmittingsaid transceive processor directs said transmit element to transmitoptical data in the first optical signal at a bit rate faster than athreshold optical data bit rate, but slower than that of said secondoptical signal.